1. Field of the Invention
The present invention relates to modular shelving, and in particular, to an improved connection for use in a modular shelving assembly.
2. Description of the Prior Art
Adjustable metal shelving (also known as "knock-down" shelving) is very popular because they purportedly provide the user with the flexibility to assemble or build shelving units to the desired configurations and needs. In particular, these adjustable shelving units allow the user to adjust the height or distance between the shelves to facilitate storage of items having different shapes and sizes.
FIGS. 1 and 2 illustrate a conventional adjustable shelving assembly. The assembly 1 has four spaced-apart posts 11, a plurality of trays 12 hanging among the four posts 11, and a plurality of sets of four tubular sleeves 13. The post 11 is an integrally formed elongated rod that is provided with a plurality of equally spaced annular peripheral grooves 111. Each tubular sleeve 13 consists of two curved pieces 131 which are engaged fittingly to form an axial through hole 132 having a configuration which conforms to the shape of the post 11. The tubular sleeve 13 has a radial inward protrusion 133 extending from inside its axial through hole 132 and which is adapted to extend into one of the annular grooves 111 on the post 11. The thickness of each tubular sleeve 13 gradually increases from top to bottom, thereby forming a diverging outer wall 134 which has a narrow top end 135 and a wide bottom end 136. The tray 12 includes a tray body 121 which has four positioning tubes 14 provided at the four corners of the tray body 121. Each positioning tube 14 has an inner diameter that is larger than the narrow top end 135 but smaller than the wide bottom end 136 of the tubular sleeves 13.
To assemble the assembly 1, a set of four tubular sleeves 13 are respectively sleeved onto the four posts 11 at an equal height. In other words, four annular grooves 111 (one from each post 11) are chosen at the same height along the respective posts. The protrusions 133 of the tubular sleeves 13 extend into the selected annular grooves 111 of equal height. The four positioning tubes 14 are then sleeved into the four posts 11, respectively, so that each positioning tube 14 slides over its corresponding tubular sleeve 13. Since the inner diameter of the positioning tubes 14 is smaller than the outer diameter of the wide bottom end 136 of the tubular sleeves 13, the positioning tubes 14 frictionally engage, and are restricted by, the wide bottom ends 136. Therefore, the positioning tubes 14 for one tray 12 are tightly fitted and stably positioned on the tubular sleeves 13, which are in turn stably positioned on the respective poles 11 by the protrusions 133 extending into the corresponding annular grooves 111. Other trays 12 can be fixed to the four poles 11 (at another height) in the same manner. To adjust the height of a tray 12, the tray 12 is moved upwardly to disengage the positioning tubes 14 from the tubular sleeves 13, and the tubular sleeves 13 positioned at another height along the posts 11 before the tray 12 is again fixed to the four tubular sleeves 13.
Although it is convenient to adjust the height of the trays 12, the use of the integrally formed posts 11 presents a storage and packing problem in that the height of the posts 11 are much longer than the trays 12, so that the posts 11 and the trays 12 must be packaged separately. Attempts have been made to provide the poles 11 in a plurality of shorter pieces that can be secured together to form a pole 11 of a desired height. One example is illustrated in U.S. Pat. No. 5,676,263 (Chang), which provides threaded connectors for threadably coupling the ends of two different post units. However, the pole structure in U.S. Pat. No. 5,676,263 (Chang) suffers from the drawback that the stability of the assembly may be compromised if the connector is not completely or properly threaded to the ends of the pole units.
To maintain their popularity and utility, adjustable shelving assemblies should accomplish two important objectives: to provide convenience in use, and to provide stability. Given the drawbacks associated with the conventional adjustable shelving units and the known prior art, there still remains a need for pole structures that can provide sufficient stability to a resulting adjustable shelving assembly, while providing the user with convenience when assembling the adjustable shelving assembly.